Projectile for training ammunition

ABSTRACT

Training ammunition in the form of a projectile having spin braking means arranged in the front part thereof. The spin braking means includes a central bore extending from the tip of the projectile partially therethrough with the rear portion of the central bore being in communication with the outer surface of the projectile via discharge channels arranged about the central bore. The rear portion of the central bore is provided with a deflecting lobe having a cross section which increases rearwardly for directing the air flow into the discharge channels in order to minimize turbulence in the air flow. The central bore and discharge channels operate in the manner of a rotary compressor with radial rotors in that air flow therethrough during the flight of a spin stabilized projectile effects braking of the projectile in a predetermined manner to reduce the flight range of the projectile. With known flight characteristics of a projectile, the cross-sectional size of the central bore and discharge channels can be selected to produce a predetermined braking effect and a predetermined flight range for the projectile.

United States Patent i191 Gawlick et a1.

Apr. 2, 1974 PROJECTILE lFOR TRAINING AMMUNITION [75] Inventors: HeinzGawlick, Furth; Arthur Schatz, Stadeln; Heinz Mothes, Geyen, all ofGermany [73] Assignee: Dynamit Nobel Aktiengesellschaft,

Troisdorf, Germany [22] Filed: Nov. 30, 1971 [21] Appl. No.: 203,401

[30] Foreign Application Priority Data Oct. 7, 1971 Germany 2149977 [52]US. Cl. 102/92.7, 244/323 [51] llnt. Cl. F42b 13/20, F42b 15/14 [58]Field of Search 102/41, 92.7; 244/323 [56] References Cited UNITEDSTATES PATENTS 1,892,158 12/1932 Matthews 102/92.7

3,713,386 l/1973 Zaid 102/41 33,746 11/1861 Matteson 244/323 35,1034/1862 Mansfield 244/323 40,538 11/1863 Halvorson..... 244/323 962,4826/1910 Wells 244/323 40,142 9/1863 Halvorson 4. 244/323 PrimaryExaminer-Benjamin A. Borchelt Assistant Examiner-C. T. Jordan Attorney,Agent, or Firm-Craig and Antonelli [57] ABSTRACT Training ammunition inthe form of a projectile having spin braking means arranged in the frontpart thereof. The spin braking means includes a central bore extendingfrom the tip of the projectile partially therethrough with the rearportion of the central bore being in communication with the outersurface of the projectile via discharge channels arranged about thecentral bore. The rear portion of the central bore is provided with adeflecting lobe having a cross section which increases rearwardly fordirecting the air flow into the discharge channels in order to minimizeturbulence in the air flow. The central bore and discharge channelsoperate in the manner of a rotary compressor with radial rotors in thatair flow therethrough during the flight of a spin stabilized projectileeffects braking of the projectile in a predetermined manner to reducethe flight range of the projectile. With known flight characteristics ofa projectile, the cross-sectional size of the central bore and dischargechannels can be selected to produce a predetermined braking effect and apredetermined flight range for the projectile.

59 Claims, 7 Drawing Figures PROJECTILE FOR TRAINING AMMUNITION Thepresent invention relates to training ammunition having a reduced flightrange and capable of being utilized on small firing ranges.

Due to the relatively long range of live ammunition, the firing of thisammunition must take place at a firing range and one is limited to asmall number of large firing ranges and practice grounds with respect tothe combat training of troups. In order to eliminate this disadvantageand to make it possible to conduct practice firing also on smallerranges, a gallery or dummy ammunition has been produced which islightweight and a short-range projectile of a synthetic resin. However,

difficulties ensued in this connection regarding the function ofautomatic weapons utilizing this type of ammunition. Although thesedifficulties could be overcome by increasing the weight of theammunition by providing the synthetic resin with chips, granules, or thelike of a heavy metal, this, in turn, was equivalent to an increasedrange of the projectile.

Another conventional way for providing a training ammunition which,except for a shortened range of the projectile, conforms as closely aspossible to the corresponding live ammunition with respect to theproperties thereof, resides in that the projectile is formed in themanner of live ammunition and is provided with a continuous centralaxial bore. The bore has an inside cross section which can be up to onethird or more of the caliber cross section, and which can additionallybe of a special configuration for the purpose of effecting an axialbraking of the projectile.

The present invention provides a training ammunition having a reducedrange wherein the projectile is controlled in an exactly predeterminedmanner by braking the spin to below the minimum spin required tomaintain the stable flight of the projectile. In this manner, the use ofthe training ammunition constructed in accordance with the presentinvention is possible on small firing ranges. An initial considerationis that the firing of the ammunition from the original weapon takesplace at a known spin angle, and a prerequisite is that the projectileleaves the barrel of the weapon at a spin speed which is so far abovethe minimum speed necessary for a stable flight that a stably traversedflight path of a desired length is the result, with a continuous brakingof the spin starting at the instant of departure. This is accomplished,according to this invention, by providing the tip portion of theammunition with a spin-braking means.

In accordance with the present invention, it is possible by appropriateconfiguration and dimensioning of the spin-braking device to brake therotation of the projectile during its flight in such a manner that thisrotation, after a flight path which is predetermined within certainlimits, falls below the minimum rotation requi'red for spinstabilization. The projectile begins to tumble, finally is pivoted by180 vertically to its axis of rotation, and continues its flight withthe rear of the projectile pointing forward. However, this is connectedwith an increase in the air resistance or drag which can be influencedby the configuration of the rear of the projectile, such that ashortened maximum range of the projectile is provided.

Accordingly, the training ammunition is usable in a similar manner tothat of live ammunition and exhibits initially the same behavior withrespect to external ballistics and consequently also the same flightpath as the live projectile. Therefore, the same sighting adjustment canbe utilized for firing the training ammunition as that for liveammunition. At the same time, the maximum firing range is smaller thanin case of live ammunition, so that the practice projectile can beutilized with great versatility on firing ranges having a smaller safetyzone.

In accordance with an embodiment of the present invention, thespin-braking means is formed as a bore of the blind-hole type startingat the tip of the projectile with the rear of the bore ending within theprojectile and being in communication with bores at the jacket of theprojectile via preferably radially disposed channels. In thisarrangement, the air entering the central bore and dammed up thereinflows via the channels and communicating bores toward the outside. Dueto appropriate arrangement and configuration of the mouths of the bores,the projectile imparts to the exiting air an impulse which is inopposition to the spin direction such that the rotation of theprojectile is braked by the amount of the impulse. Since thisspin-braking means basically has the effect of a rotary compressor, theenergy requirement of which is covered by the rotational energy of theprojectile, the central bore and the dis charge channels are formed inaccordance with the known principles of rotary compressors with radialrotors. Thus, in dependence on the predetermined external ballistic dataof the projectile, the discharge channels and central bore of the spinbraking means may be designed to have the effect of a radial rotor,initially, i.e. without lengthy experiments, in such a manner that thedecrease in rotational energy and thus also the passing of the stabilitylimit of the projectile toward instability take place in a predeterminedmanner.

According to a feature of the present invention, the inside diameter ofthe central bore is selected to be between approximately 10 and 40% ofthe caliber of the projectile. This diameter range is preferable since asmaller inside diameter could provide an insufficient flow of airthrough the central bore and a larger inside diameter withcorrespondingly shorter discharge channels could undesirably reduce theenergy transfer to the exiting air. In order to ensure that the airflows off from the central bore as unhindered as possible, it isadvantageous, according to another feature of the invention, to choosethe inside entrance cross section of all discharge channels takentogether to be larger by at least about 20% than the inside crosssection of the central bore. Other features of the present inventioninclude the arranging of the outlet openings of the discharge channelsin the cylindrical portion of the jacket of the projectile in order toobtain as large a pressure gradient as possible for the air flow throughthe central bore and through the discharge channels, thereby enhancingthe discharge of air. Moreover, in order to keep the influence of anyasymmetrically effective transverse forces due to the air flow throughthe projectile as small as possible, the discharge channels may bepositioned at least approximately in the zone of the cross-sectionalplane defined by the center of gravity of the projectile. In thismanner, the resultant of any uncompensated lateral flow forces withinthe discharge channels, which are disposed, for example, in a plane oralso on a conical surface, is arranged to be effective at leastapproximately in the center of gravity of the projectile,

whereby any pitch moments are advantageously diminished or eliminated.

In accordance with another embodiment of the present invention, theprojectile which can be formed in one piece, for example by casting, isformed of different mating portions in order to keep the manufacturingexpenses as low as possible. The projectile is divided in the region ofthe discharge channels in such a manner that one part having a lugengages into a corresponding recess of the other part, and the dischargechannels are each formed as two partial bores which are preferablyinclined toward each other and arranged in the lug and in the wall ofthe recess.

According to a further embodiment of the invention which provides aneconomical construction suitable for a mass production, the dischargechannels are formed in separate components as a radial rotor member. Inthis manner, the discharge channels can be joined to the projectile inthe zone of the rear end of the central bore. That is, the central boreextends completely through the front part of the projectile and theradial rotor is attached at the rear of the projectile to close off thecentral bore.

The rigid connection of the two parts of the projectile with each other,or of the individually manufactured radial rotor with the projectiledivided in the zone of the rear end of the central bore, can be effectedin a conventional manner, depending on the particular situation, forexample depending on the materials employed or on the forces effectiveon the projectile, by frictional contact in the manner of a press fit,or also by means of a threaded, plug-in, glue, weld, or solderconnection, or the like.

In accordance with another feature of the present invention, adeflecting lobe with a cross section that increases in the flowdirection is suitably disposed at the rear end of the central bore inorder to minimize turbulence in the air flow from the central bore tothe discharge channels. This lobe can have a conical configuration, forexample, wherein the diameter of the base corresponds to the diameter ofthe central bore. However, preferably the design ofthe deflecting lobeis such that it has a concave surface in its part under the effect ofthe air flow.

It is therefore an object of the present invention to provide trainingammunition which overcomes the disadvantages of prior art constructions.

It is another object of the present invention to provide trainingammunition having a predetermined flight path which is of much shorterrange than live ammunition.

It is still another object of the present invention to provide trainingammunition in the form of a projectile having a spin-braking means inthe tip portion thereof which is formed in accordance with the knownprinciples of rotary compressors with radial rotors such that apredetermined spin-braking is effected.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description, whentaken in connection with the accompanying drawings which show, forpurposes of illustration only, several embodiments in accordance withthe present invention, and wherein:

FIG. 1 is a longitudinal sectional view of a projectile exiting from abarrel of a weapon in accordance with the present invention,

FIG. 2 is a longitudinal sectional view of another embodiment of aprojectile in accordance with the present invention,

FIG. 3 is a cross-sectional view taken along line III- ---III of theprojectile of FIG. 2,

FIG. 4 is a fragmentary longitudinal sectional view of anotherprojectile embodiment wherein the radial rotor is formed as a separatecomponent,

FIGS. 5a and 5b are plan and elevational views, respectively, of theradial rotor of FIG. 4, and

FIG. 6 is a cross-sectional view of another radial rotor in accordancewith the present invention.

Referring now to the drawings wherein like reference numerals are usedthroughout the several views to designate like parts and moreparticularly to FIG. I which shows a training projectile l which isintegrally formed, for example by casting, and having a caliber Dexiting from the barrel 25 of a weapon. The projectile is provided witha central bore 2 having an inside diameter D, and discharge channels 3extending therefrom. The discharge channels have a height h, at theentrance and a height h at the exit. At the rear end of the central bore2, a rotationally symmetrical deflecting lobe 4 is integrally formedwith the projectile. The discharge channels 3 are disposed approximatelyin the zone of the cross-sectional plane determined by the center ofgravity of the projectile, so that any transverse forces due to the airflow indicated by the arrows A exert only a minor influence on theprojectile. The projectile l is constructed in a conventional manner ofsteel, brass, aluminum, or like materials.

In FIG. 2 the projectile 1 is shown as being divided in the region ofthe discharge channels 3, only one channel being shown for reasons ofclarity, in such a manner that the rear part 5 having a lug 6 engages acorresponding recess of the front part 7. Both parts are connected witheach other by means of a threaded joint. A deflecting lobe 8, shown inan elevational view, which is manufactured separately for reasons offacilitating the production of the device, is inserted in the rear endof the central bore 2 and held in position by means of a collar 9 and abottom section 10 threadedly joined to the rear part 5. As shown, thesurface 15 of the deflecting lobe 8, which is under the effect of theair flow, is concave and formed to be rotationally symmetrical. Anannular guide band 11 of, for example, copper, brass, or lead is securedabout the rear part 5 and serves to provide a better seal in the barrelof the firearm. The projectile is also provided with a signal flarecartridge 12 which is inserted in the bottom section 10 and a targetmarking charge 13 is arranged in the front part 7. It would, of .course,be possible to provide, in place of the signal flare cartridge 12 and/orthe target marking charge 13, an impact bursting charge or the like. Thetip 14 of the projectile can be produced, for example, of a syntheticresin, aluminum, or also of steel. The selection of the material dependson the weight to be imparted to the projectile, and whether apyrotechnic target marking is desired. In this case, the tip of theprojectile is suitably made of a readily deformable material, preferablypolyethylene or aluminum.

The cross section taken along line IIIIII of FIG. 2, illustrated in FIG.3, shows the distribution of the discharge channels 3 between the lug 6and the front part 7 into two mutually inclined partial bores 16 and 17.If the spin-stabilized projectile rotates, in accordance with the arrowB, in the counterclockwise direction, the mutual inclination of thepartial bores 16 and 17, provided in the same direction, effects thelargest possible spin-braking, in that a rotational force in theopposite direction is effected. Of course, depending upon the requiredbraking effect, it is also possible to provide an oppositely directedinclination, or both partial bores can also be disposed so that they arealigned with each other, so that the discharge channels are thusoriented in a purely radial direction.

As shown in FIG. 4, a rotor 18 which is formed as a separate componentis inserted into the projectile 1 which is divided into a rear part 5and a front part 7. The radial rotor 18 is secured by means of pins 19in the rear part 5 with the rear and front parts being connected bymeans of the thread 20. In the front part 7, perforations 21 areprovided, which are associated with the discharge channels 3 formed inthe radial rotor 18, in order to make it possible for the air to exitlaterally. The front part 7, as distinguished from FIG. 2, ismanufactured integrally with the tip of the projectile, which portion isnot shown.

The radial rotor 18 of FIG. 4 which is illustrated in top plan andelevation views in FIGS. 5a and 5b is provided with six radiallydisposed vanes 22 in a uniform distribution such that the dischargechannels 3 are formed between these vanes. As shown in FIG. 5b, theheight of the vanes 22 decreases in the outward radial direction withthe mutual distance between vanes increasing in this direction. Bothparameters are adapted to each other in such a manner that thecross-sectional modification of the discharge channels 3 obtainedthereby makes it exactly possible to achieve the desired effect on theair flow. The radial rotor 18 is preferably manufactured from a metalwhich can be processed by means of the die-casting method, such as, forexample, aluminum, zinc alloys, or like materials.

In FIG. 6, there is shown another embodiment of a radial rotor 23 in across-sectional view with the section taken close to the lower end ofthe deflecting lobe 4. In this embodiment, the vanes 24 are curved inthe manner of turbine vanes. The connection with the projectile partscan be effected in the same manner as shown in FIG. 4, but, of course,can also be accomplished in another conventional manner.

In accordance with the above-described features and principles ofoperation, a spin-stabilized training projectile having a desiredshortened range may be produced. An example of such a projectile is aprojectile having the caliber D 105 mm., a muzzle velocity ofapproximately 800 m./sec., and a peripheral speed at the muzzle of theweapon of approximately 30 m./sec. which is in the same order ofmagnitude as a rotary compressor. The pressure difference between thetip of the projectile and the cylindrical zone of the jacket of theprojectile has, depending on the configuration of the tip, an upperlimit of approximately 1kp./cm This projectile was designed to fallbelow the stability limit after approximately 1,500 meters of firingrange and then to descend to the ground as quickly as possible. On thebasis of predetermined calculations based on the principles of rotarycompressors, the projectile was constructed in accordance with FIGS. 2and 3 to have four bores for the discharge channels 16, 17. Each channelhad a diameterof 12.5 mm. and a bend angle of 45 with the insidediameter D, of the central bore 2 being 30 mm. In practice firing testswith this projectile, photographic records of the flight path of theprojectile disclosed deviations after approximately 1,500 meters as aresult of the projectile becoming unstable in flight, thereby providingthe required shortening of the maximum range of the projectile.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. It should therefore beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

We claim:

1. Training ammunition comprising a projectile having a spin stabilizedflight upon launching from a barrel of a weapon and spin-braking meansarranged in said projectile serving as a rotary compressor with radialrotors for braking the spin stabilized flight of said projectile toreduce the maximum flight range thereof, said spin-braking meansincluding a central bore extending from the tip of said projectilepartially therethrough, said central bore having the rear portionthereof in communication with the outer surface of said projectile viadischarge channels arranged about said central bore, whereby the spinstabilized flight of said projectile is braked by the flow of airthrough said central bore and said discharge channels.

2. Training ammunition as defined in claim 1, wherein said central boreand said discharge channels are provided with inner cross sections ofpredetermined size in accordance with the flight characteristics of saidprojectile to provide a predetermined braking effect on said projectile.

3. Training ammunition as defined in claim 2, wherein said dischargechannels have an entrance opening at said central bore and an exitopening at the outer surface of said projectile, said exit opening beingat an angular inclination with respect to said entrance opening.

4. Training ammunition as defined in claim 3, wherein the angularinclination of said exit opening is in the spin direction of saidprojectile.

5. Training ammunition as defined in claim 1, wherein said dischargechannels are symmetrically arranged about said central bore.

6. Training ammunition as defined in claim 5, wherein said dischargechannels have center lines lying in a plane substantially transverse tothe axis of said central bore.

7. Training ammunition as defined in claim 6, wherein said projectile isof a predetermined caliber and said central bore is provided with aninside diameter of between approximately 10 percent and 40 percent ofsaid predetermined caliber.

8. Training ammunition as defined in claim 7, wherein said dischargechannels have an entrance opening at said central bore and the totalentrance cross section of the combined discharge channels is larger byat least approximately 20 percent than the inside cross section of saidcentral bore.

9. Training ammunition as defined in claim 8, wherein said projectilehas a cylindrical portion and said discharge channels have an exitopening at the outer surface of said projectile in the cylindricalportion thereof.

10. Training ammunition as defined in claim 9, wherein said projectileis provided with a predetermined center of gravity thereof and saiddischarge channels are disposed approximately in the region of thecross-sectional plane determined by said center of gravity.

11. Training ammunition as defined in claim 10, wherein said projectileincludes at least a first and second part joined together in the regionof said discharge channels, said first part being provided with a lugportion and said second part being provided with a recess portion forreceiving said lug portion, each of said discharge channels being formedas two partial bores, one of said bores being provided in the lugportion of said first part and the other bore being provided in the wallof said recess portion of said second part.

12. Training ammunition as defined in claim 11, wherein said two boresare at an angular inclination with respect to each other.

13. Training ammunition as defined in claim 12, wherein said centralbore is provided at the rear end thereof with a deflecting lobe having across section which increases rearwardly in the flow direction.

14. Training ammunition as defined in claim 13, wherein said deflectinglobe is provided with a concave surface for directing the air flow intosaid discharge channels.

15. Training ammunition as defined in claim 1, wherein said projectileis of a predetermined caliber and said central bore is provided with aninside diameter of between approximately percent and 40 percent of saidpredetermined caliber.

16. Training ammunition as defined in claim 15, wherein said dischargechannels have an entrance opening at said central bore and the totalentrance cross section of the combined discharge channels is larger byat least approximately percent than the inside cross section of saidcentral bore.

17. Training ammunition as defined in claim 15, wherein said projectileincludes at least a first and second part joined together in the regionof said discharge channels, said first part being provided with a lugportion and said second part being provided with a recess portion forreceiving said lug portion, each of said discharge channels being formedas two partial bores, one of said bores being provided in the lugportion of said first part and the other bore being provided in the wallof said recess portion of said second part.

18. Training ammunition as defined in claim 17, wherein said two boresare at an angular inclination with respect to each other.

19. Training ammunition as defined in claim 18, wherein said centralbore is provided at the rear end thereof with a deflecting lobe having across section which increases rearwardly in the flow direction.

20. Training ammunition as defined in claim 19, wherein said deflectinglobe is provided with a concave surface for directing the air flow intosaid discharge channels.

21. Training ammunition as defined in claim 15, wherein said projectileis provided with a first part having said central bore therein and saiddischarge channels are provided in a second part adapted for connectionwith said first part in the region of the rear end of said central bore.

22. Training ammunition as defined in claim 16, wherein said projectilehas a cylindrical portion and said discharge channels have an exitopening at the outer surface of said projectile in the cylindricalportion thereof.

23. Training ammunition as defined in claim 22, wherein said projectileis provided with a predetermined center of gravity thereof and saiddischarge channels are disposed approximately in the region of thecross-sectional plane determined by said center of gravity.

24. Training ammunition as defined in claim 23, wherein said dischargechannels are symmetrically arranged about said central bore.

25. Training ammunition as defined in claim 16, wherein said projectileincludes at least a first and second part joined together in the regionof said discharge channels, said first part being provided with a lugportion and said second part being provided with a recess portion forreceiving said lug portion, each of said discharge channels being formedas two partial bores, one of said bores being provided in the lugportion of said first part and the other bore being provided in the wallof said recess portion of said second part.

26. Training ammunition as defined in claim 25, wherein said two boresare at an angular inclination with respect to each other.

27. Training ammunition as defined in claim 26, wherein said centralbore is provided at the rear end thereof with a deflecting lobe having across section which increases rearwardly in the flow direction.

28. Training ammunition as defined in claim 27, wherein said deflectinglobe is provided with a concave surface for directing the air flow intosaid discharge channels.

29. Training ammunition as defined in claim 16, wherein said projectileis provided with a first part having said central bore therein and saiddischarge channels are provided in a second part adapted for connectionwith said first part in the region of the rear end of said central bore.

30. Training ammunition as defined in claim 1, wherein said projectilehas a cylindrical portion and said discharge channels have an exitopening at the outer cylindrical surface of said projectile in thecylindrical portion thereof.

31. Training ammunition as defined in claim 30, wherein said projectileis provided with a first part having said central bore therein and saiddischarge channels are provided in a second part adapted for connectionwith said first part in the region of the rear end of said central bore.

32. Training ammunition as defined in claim 1, wherin said projectile isprovided with a predetermined center of gravity thereof and saiddischarge channels are disposed approximately in the region of thecrosssectional plane determined by said center of gravity.

33. Training ammunition as defined in claim 32, wherein said projectileincludes at least a first and second part joined together in the regionof said discharge channels, said first part being provided with a lugportion and said second part being provided with a recess portion forreceiving said lug portion, each of said discharge channels being formedas two partial bores, one of said bores being provided in the lugportion of said first part and the other bore being provided in the wallof said recess portion of said second part.

34. Training ammunition as defined in claim 33, wherein said two boresare at an angular inclination with respect to each other.

35. Training ammunition as defined in claim 34, wherein said centralbore is provided at the rear end thereof with a deflecting lobe having across section which increases rearwardly in the flow direction.

36. Training ammunition as defined in claim 35, wherein said deflectinglobe is provided with a concave surface for directing the air flow intosaid discharge channels.

37. Training ammunition as defined in claim 32, wherein said projectileis provided with a first part having said central bore therein and saiddischarge chan nels are provided in a second part adapted for connectionwith said first part in the region of the rear end of said central bore.

38. Training ammunition as defined in claim 1, wherein said projectileincludes at least a first and second part joined together in the regionof said discharge channels, said first part being provided with a lugportion and said second part being provided with a recess portion forreceiving said lug portion, each of said discharge channels being formedas two partial bores, one of said bores being provided in the lugportion of said first part and the other bore being provided in the wallof said recess portion of said second part.

39. Training ammunition as defined, in claim 38, wherein said two boresare at an angular inclination with respect to each other.

40. Training ammunition as defined in claim 1, wherein said projectileis provided with a first part having said central bore therein and saiddischarge channels are provided in a second part adapted for connectionwith said first part in the region of the rear end of said central bore.

41. Training ammunition as defined in claim 40, wherein said second partis provided with a deflecting lobe having a cross section whichincreases rearwardly in the flow direction, said deflecting lobe beingdisposed on said part at the junction of said discharge channels andadapted to be arranged along the axis of the central bore at the rearend thereof.

42. Training ammunition as defined in claim 41, wherein said deflectinglobe is provided with a concave surface for directing the air flow intosaid discharge channels.

43. Training ammunition as defined in claim 1, wherein said central boreis provided at the rear end thereof with a deflecting lobe having across section which increases rearwardly in the flow direction.

44. Training ammunition as defined in claim 43, wherein said deflectinglobe is provided with a concave surface for directing the air flow intosaid discharge channels.

45. Training ammunition as defined in claim 1, wherein said dischargechannels have an entrance opening at said central bore and the totalentrance cross section of the combined discharge channels is larger byat least approximately percent than the inside cross section of saidcentral bore.

46. Training ammunition as defined in claim 1, wherein said projectileis provided with a first part having said central bore therein, saidfirst part having a cylindrical portion with apertures arranged in theregion ofthe rear end of said central bore and extending to the outercylindrical surface of said projectile, and a second part havingdischarge channels adapted for connection with said first part in theregion of the rear end of said central bore, each of said dischargechannels being arranged for communication with a corresponding apertureof said first part for directing the air flow from said central boreinto said corresponding aperture.

47. Training ammunition as defined in claim 46, wherein said second partis provided with a deflecting lobe having a cross section whichincreases rearwardly in the flow direction, said deflecting lobe beingdisposed on said part at the junction of said discharge channels andadapted to be arranged along the axis of the central bore at the rearend thereof.

48. Training ammunition as defined in claim 47, wherein said deflectinglobe is provided with a concave surface for directing the air flow intosaid discharge channels.

49. Training ammunition as defined in claim 48, wherein said dischargechannels are formed by radially extending vanes.

50. Training ammunition as defined in claim 49, wherein the height ofthe vanes decreases and the distance between adjacent vanes increases inthe outward radial direction.

51. Training ammunition as defined in claim 49, wherein said vanes arecurved in the outward radial direction.

52. Training ammunition as defined in claim 51, wherein the height ofthe vanes decreases and the distance between adjacent vanes increases inthe outward radial direction.

53. Training ammunition as defined in claim 1, wherein said projectileincludes a first part having said central bore therein, said first parthaving a cylindrical portion having apertures arranged about theperiphery thereof in the region of the rear end of said central bore, asecond part connected to said first part, and a third part forming saiddischarge channels being positioned on said second part in the region ofthe rear end of said central bore and arranged for communication withsaid apertures of said first part for directing the air flow from saidcentral bore into said apertures.

54. Training ammunition as defined in claim 53, wherein said third partis a radial rotor member connected with said second part.

55. An arrangement for training ammunition comprising a projectile, aweapon for launching said projectile and imparting a rotation to saidprojectile so as to provide a spin stabilized flight of said projectile,said projectile including braking means for applying rotation retardingforces to said spin stabilized projectile so as to brake the spinstabilized flight of said projectile and making said projectile unstablethereby limiting the maximum flight range of said projectile.

56. An arrangement as defined in claim 55, wherein said braking means isarranged within said projectile and includes a central bore extendingfrom the tip of said projectile partially therethrough, said centralbore having the rear portion thereof in communication with the outersurface of said projectile via discharge channels arranged about saidcentral bore, whereby the spin stabilized flight of said projectile isretarded by the flow of air through the central bore and the dischargechannels.

57. A method for controlling the flight range of spin stabilizedprojectiles for training purposes comprising the steps of launching aprojectile, imparting a rotation to the projectile so as to provide aspin stabilized flight for the projectile, and applying a spin retardingforce to the spin stabilized projectile to break the rotation of illprojectile includes a central bore extending from the tip of theprojectilepartially therethrough, the central bore having the rearportion thereof in communication with the outer surface of theprojectile via discharge channels arranged about the central bore, thestep of applying a retarding force including the directing of the airflow through the central bore and the discharge channels to brake thespin stabilized flight of the projectile.

1. Training ammunition comprising a projectile having a spin stabilizedflight upon launching from a barrel of a weapon and spin-braking meansarranged in said projectile serving as a rotary compressor with radialrotors for braking the spin stabilized flight of said projectile toreduce the maximum flight range thereof, said spin-braking meansincluding a central bore extending from the tip of said projectilepartially therethrough, said central bore having the rear portionthereof in communication with the outer surface of said projectile viadischarge channels arranged about said central bore, whereby the spinstabilized flight of said projectile is braked by the flow of airthrough said central bore and said discharge channels.
 2. Trainingammunition as defined in claim 1, wherein said central bore and saiddischarge channels are provided with inner cross sections ofpredetermined size in accordance with the flight characteristics of saidprojectile to provide a predetermined braking effect on said projectile.3. Training ammunition as defined in claim 2, wherein said dischargechannels have an entrance opening at said central bore and an exitopening at the outer surface of said projectile, said exit opening beingat an angular inclination with respect to said entrance opening. 4.Training ammunition as defined in claim 3, wherein the angularinclination of said exit opening is in the spin direction of saidprojectile.
 5. Training ammunition as defined in claim 1, wherein saiddischarge channels are symmetrically arranged about said central bore.6. Training ammunition as defined in claim 5, wherein said dischargechannels have center lines lying in a plane substantially transverse tothe axis of said central bore.
 7. Training ammunition as defined inclaim 6, wherein said projectile is of a predetermined caliber and saidcentral bore is provided with an inside diameter of betweenapproximately 10 percent and 40 percent of said predetermined caliber.8. Training ammunition as defined in claim 7, wherein said dischargechannels have an entrance opening at said central bore and the totalentrance cross section of the combined discharge channels is larger byat least approximately 20 percent than the inside cross section of saidcentral bore.
 9. Training ammunition as defined in claim 8, wherein saidprojectile has a cylindrical portion and said discharge channels have anexit opening at the outer surface of said projectile in the cylindricalportion thereof.
 10. Training ammunition as defined in claim 9, whereinsaid projectile is provided with a predetermined center of gravitythereof and said discharge channels are disposed approximately in theregion of the cross-sectional plane determined by said center ofgravity.
 11. Training ammunition as defined in claim 10, wherein saidprojectile includes at least a first and second part joined together inthe region of said discharge channels, said first part being providedwith a lug portion and said second part being provided with a recessportion for receiving said lug portion, each of said discharge channelsbeing formed as two partial bores, one of said bores being provided inthe lug portion of said first part and the other bore being provided inthe wall of said recess portion of said second part.
 12. Trainingammunition as defined in claim 11, wherein said two bores are at anangular inclination with respect to each other.
 13. Training ammunitionas defined in claim 12, wherein said central bore is provided at therear end thereof with a deflecting lobe having a cross section whichincreases rearwardly in the flow direction.
 14. Training ammunition asdefined in claim 13, wherein said deflecting lobe is provided with aconcave surface for directing the air flow into said discharge channels.15. Training ammunition as defined in claim 1, wherein said projectileis of a predetermined caliber and said centraL bore is provided with aninside diameter of between approximately 10 percent and 40 percent ofsaid predetermined caliber.
 16. Training ammunition as defined in claim15, wherein said discharge channels have an entrance opening at saidcentral bore and the total entrance cross section of the combineddischarge channels is larger by at least approximately 20 percent thanthe inside cross section of said central bore.
 17. Training ammunitionas defined in claim 15, wherein said projectile includes at least afirst and second part joined together in the region of said dischargechannels, said first part being provided with a lug portion and saidsecond part being provided with a recess portion for receiving said lugportion, each of said discharge channels being formed as two partialbores, one of said bores being provided in the lug portion of said firstpart and the other bore being provided in the wall of said recessportion of said second part.
 18. Training ammunition as defined in claim17, wherein said two bores are at an angular inclination with respect toeach other.
 19. Training ammunition as defined in claim 18, wherein saidcentral bore is provided at the rear end thereof with a deflecting lobehaving a cross section which increases rearwardly in the flow direction.20. Training ammunition as defined in claim 19, wherein said deflectinglobe is provided with a concave surface for directing the air flow intosaid discharge channels.
 21. Training ammunition as defined in claim 15,wherein said projectile is provided with a first part having saidcentral bore therein and said discharge channels are provided in asecond part adapted for connection with said first part in the region ofthe rear end of said central bore.
 22. Training ammunition as defined inclaim 16, wherein said projectile has a cylindrical portion and saiddischarge channels have an exit opening at the outer surface of saidprojectile in the cylindrical portion thereof.
 23. Training ammunitionas defined in claim 22, wherein said projectile is provided with apredetermined center of gravity thereof and said discharge channels aredisposed approximately in the region of the cross-sectional planedetermined by said center of gravity.
 24. Training ammunition as definedin claim 23, wherein said discharge channels are symmetrically arrangedabout said central bore.
 25. Training ammunition as defined in claim 16,wherein said projectile includes at least a first and second part joinedtogether in the region of said discharge channels, said first part beingprovided with a lug portion and said second part being provided with arecess portion for receiving said lug portion, each of said dischargechannels being formed as two partial bores, one of said bores beingprovided in the lug portion of said first part and the other bore beingprovided in the wall of said recess portion of said second part. 26.Training ammunition as defined in claim 25, wherein said two bores areat an angular inclination with respect to each other.
 27. Trainingammunition as defined in claim 26, wherein said central bore is providedat the rear end thereof with a deflecting lobe having a cross sectionwhich increases rearwardly in the flow direction.
 28. Trainingammunition as defined in claim 27, wherein said deflecting lobe isprovided with a concave surface for directing the air flow into saiddischarge channels.
 29. Training ammunition as defined in claim 16,wherein said projectile is provided with a first part having saidcentral bore therein and said discharge channels are provided in asecond part adapted for connection with said first part in the region ofthe rear end of said central bore.
 30. Training ammunition as defined inclaim 1, wherein said projectile has a cylindrical portion and saiddischarge channels have an exit opening at the outer cylindrical surfaceof said projectile in the cylindrical portion thereof.
 31. Trainingammunition as definEd in claim 30, wherein said projectile is providedwith a first part having said central bore therein and said dischargechannels are provided in a second part adapted for connection with saidfirst part in the region of the rear end of said central bore. 32.Training ammunition as defined in claim 1, wherin said projectile isprovided with a predetermined center of gravity thereof and saiddischarge channels are disposed approximately in the region of thecross-sectional plane determined by said center of gravity.
 33. Trainingammunition as defined in claim 32, wherein said projectile includes atleast a first and second part joined together in the region of saiddischarge channels, said first part being provided with a lug portionand said second part being provided with a recess portion for receivingsaid lug portion, each of said discharge channels being formed as twopartial bores, one of said bores being provided in the lug portion ofsaid first part and the other bore being provided in the wall of saidrecess portion of said second part.
 34. Training ammunition as definedin claim 33, wherein said two bores are at an angular inclination withrespect to each other.
 35. Training ammunition as defined in claim 34,wherein said central bore is provided at the rear end thereof with adeflecting lobe having a cross section which increases rearwardly in theflow direction.
 36. Training ammunition as defined in claim 35, whereinsaid deflecting lobe is provided with a concave surface for directingthe air flow into said discharge channels.
 37. Training ammunition asdefined in claim 32, wherein said projectile is provided with a firstpart having said central bore therein and said discharge channels areprovided in a second part adapted for connection with said first part inthe region of the rear end of said central bore.
 38. Training ammunitionas defined in claim 1, wherein said projectile includes at least a firstand second part joined together in the region of said dischargechannels, said first part being provided with a lug portion and saidsecond part being provided with a recess portion for receiving said lugportion, each of said discharge channels being formed as two partialbores, one of said bores being provided in the lug portion of said firstpart and the other bore being provided in the wall of said recessportion of said second part.
 39. Training ammunition as defined in claim38, wherein said two bores are at an angular inclination with respect toeach other.
 40. Training ammunition as defined in claim 1, wherein saidprojectile is provided with a first part having said central boretherein and said discharge channels are provided in a second partadapted for connection with said first part in the region of the rearend of said central bore.
 41. Training ammunition as defined in claim40, wherein said second part is provided with a deflecting lobe having across section which increases rearwardly in the flow direction, saiddeflecting lobe being disposed on said part at the junction of saiddischarge channels and adapted to be arranged along the axis of thecentral bore at the rear end thereof.
 42. Training ammunition as definedin claim 41, wherein said deflecting lobe is provided with a concavesurface for directing the air flow into said discharge channels. 43.Training ammunition as defined in claim 1, wherein said central bore isprovided at the rear end thereof with a deflecting lobe having a crosssection which increases rearwardly in the flow direction.
 44. Trainingammunition as defined in claim 43, wherein said deflecting lobe isprovided with a concave surface for directing the air flow into saiddischarge channels.
 45. Training ammunition as defined in claim 1,wherein said discharge channels have an entrance opening at said centralbore and the total entrance cross section of the combined dischargechannels is larger by at least approximately 20 percent than the insidecross section of said centrAl bore.
 46. Training ammunition as definedin claim 1, wherein said projectile is provided with a first part havingsaid central bore therein, said first part having a cylindrical portionwith apertures arranged in the region of the rear end of said centralbore and extending to the outer cylindrical surface of said projectile,and a second part having discharge channels adapted for connection withsaid first part in the region of the rear end of said central bore, eachof said discharge channels being arranged for communication with acorresponding aperture of said first part for directing the air flowfrom said central bore into said corresponding aperture.
 47. Trainingammunition as defined in claim 46, wherein said second part is providedwith a deflecting lobe having a cross section which increases rearwardlyin the flow direction, said deflecting lobe being disposed on said partat the junction of said discharge channels and adapted to be arrangedalong the axis of the central bore at the rear end thereof.
 48. Trainingammunition as defined in claim 47, wherein said deflecting lobe isprovided with a concave surface for directing the air flow into saiddischarge channels.
 49. Training ammunition as defined in claim 48,wherein said discharge channels are formed by radially extending vanes.50. Training ammunition as defined in claim 49, wherein the height ofthe vanes decreases and the distance between adjacent vanes increases inthe outward radial direction.
 51. Training ammunition as defined inclaim 49, wherein said vanes are curved in the outward radial direction.52. Training ammunition as defined in claim 51, wherein the height ofthe vanes decreases and the distance between adjacent vanes increases inthe outward radial direction.
 53. Training ammunition as defined inclaim 1, wherein said projectile includes a first part having saidcentral bore therein, said first part having a cylindrical portionhaving apertures arranged about the periphery thereof in the region ofthe rear end of said central bore, a second part connected to said firstpart, and a third part forming said discharge channels being positionedon said second part in the region of the rear end of said central boreand arranged for communication with said apertures of said first partfor directing the air flow from said central bore into said apertures.54. Training ammunition as defined in claim 53, wherein said third partis a radial rotor member connected with said second part.
 55. Anarrangement for training ammunition comprising a projectile, a weaponfor launching said projectile and imparting a rotation to saidprojectile so as to provide a spin stabilized flight of said projectile,said projectile including braking means for applying rotation retardingforces to said spin stabilized projectile so as to brake the spinstabilized flight of said projectile and making said projectile unstablethereby limiting the maximum flight range of said projectile.
 56. Anarrangement as defined in claim 55, wherein said braking means isarranged within said projectile and includes a central bore extendingfrom the tip of said projectile partially therethrough, said centralbore having the rear portion thereof in communication with the outersurface of said projectile via discharge channels arranged about saidcentral bore, whereby the spin stabilized flight of said projectile isretarded by the flow of air through the central bore and the dischargechannels.
 57. A method for controlling the flight range of spinstabilized projectiles for training purposes comprising the steps oflaunching a projectile, imparting a rotation to the projectile so as toprovide a spin stabilized flight for the projectile, and applying a spinretarding force to the spin stabilized projectile to break the rotationof the projectile so as to render the projectile unstable within thenormal maximum range of the projectile.
 58. A method as defined in claim57, wherein the step of impArting a rotation to the projectile includesthe step of spinning the projectile in a first direction to effect aspin stabilized flight thereof and the step of applying a retardingforce includes the step of applying a force component in a direction inopposition to the first direction.
 59. A method as defined in claim 57,wherein the projectile includes a central bore extending from the tip ofthe projectile partially therethrough, the central bore having the rearportion thereof in communication with the outer surface of theprojectile via discharge channels arranged about the central bore, thestep of applying a retarding force including the directing of the airflow through the central bore and the discharge channels to brake thespin stabilized flight of the projectile.